Bayer subsidiary BlueRock has become the first company to report initial success treating Parkinson's disease in humans using an experimental stem cell therapy, the drugmaker said on Wednesday. The hunt for Parkinson's treatments has seen many setbacks over decades. Bayer said that one year into a Phase I trial with 12 volunteers, BlueRock's therapy was shown to be well-tolerated and that transplanted cells grew as intended in patients' brains.